Thermal mechanical mineral piercing



Oct. 19, 1965 H. c. ROLSETH ETAL 3,212,592

THERMAL MECHANICAL MINERAL PIERCING Original Filed Feb 16, 1961 2 Sheets-Sheet 1 A T TORNE V Och 1965 H. c. ROLSETH ETAL THERMAL MECHANICAL MINERAL PIERCING Original Filed Feb. 16, 1961 2 Sheets-Sheet 2 INVENTORS HAROLD C. ROLSETH CORNELIUS S. ARNOLD W. GEORGE KUNZ A T TORNEV United States Patent 3,212,592 THERMAL MECHANICAL MINERAL PIERCING Harold C. Rolseth, New Brunswick, and Cornelius S. Arnold, Cranford, N.J., and Walter George Kuuz, Claymont, Del., assignors to Union Carbide Corporation, a corporation of New York Continuation of application Ser. No. 89,879, Feb. 16, 1961. This application Dec. 13, 1963, Ser. No. 331,089

7 Claims. (CL 175-14) This application is a continuation of our copending application Serial No. 89,879, filed February 16, 1961, now abandoned.

This invention relates to thermal-mechanical piercing an elongated hole in a mineral body.

The flame mineral processes heretofore employed have relied upon thermal spalling, which is limited to rock composed of constituents having different coeflicients of thermal expansion. When a surface portion of such rock is heated to a high temperature, differential expansion of such constituents takes place, causing thermally induced stresses to flake away such heated surface portions.

Many rocks contain significant quantities of low melting, elastic or soft materials, many of which decompose at relatively low temperatures. Such rocks tend to melt in the heat of the burner flame instead of spalling, thus limiting the prior process to relatively few rocks, and requiring reliance upon the present slow and expensive process of cold mechanical drilling for the majority of rocks.

It is, therefore, the main object of the present invention to provide method and apparatus for thermal mechanical piercing of non-spallable rocks. Other objects are to provide method and apparatus for successfully drilling blast holes in most types of rocks.

According to the present invention, high temperature flames are applied to the mineral body to heat the surface thereof to an elevated temperature below that at which the mineral will spall or melt but sufficiently high to cause said surface to become friable, and the so heated friable surface is subjected to mechanical rolling contact to remove the mineral chips and expose a new surface to said flame. The mineral surface is preferably heated to between 800 and 2000 F. The flames are preferably rotated alternately with the rolling contact of planetary cutters.

In the drawings:

FIGURE 1 is a vertical axial section through a blowpipe burner and drill head, according to and for carrying out the method of, the preferred embodiment of the present invention;

FIGURE 2 is a partial axial section taken at right angles to FIGURE 1; and

FIGURE 3 is a substantially horizontal section taken along the line 33 of FIGURE 1.

The thermal mechanical piercing apparatus comprises a blowpipe consisting essentially of a burner and a bit head 12. The blowpipe is provided with a header 14 having an oxygen passage 15 and a fuel passage 16 for supplying the burner nozzle 18. The fuel passage 16 leads to a fuel injector 19 and the oxygen passage 15 leads to the space between the header 14 and the nozzle 18, to discharge atomized fuel into the combustion chamber 20 inside the nozzle 18 above the orifice tip 22.

As shown in FIGURES 2 and 3, the orifice tip 22 is provided with flame ports 23 and 24 diverging at an 3,212,592 Patented Get. 19, 1965 ice angle not more than 45 to the blowpipe axis, for directmg flames onto the surface of the mineral body.

The bit head 12 encloses the burner 10 and extendsbelow the orifice tip 22 to provide inwardly converging axles 26 and 27 on which are journaled planetary drill lits 28 and 29 for annular rolling contact with the mineral ody.

As shown in FIGURE 2, cooling water is supplied by passage 32 to header 14 and there exists via opening 34 to enter the burner assembly through holes 36, from which the flow is through boring 38 to annulus 40. There the flow is divided between drillings 42, 44 and 46 which direct the water to the burner face and exterior surfaces of the cutter teeth, and drilling 48 which conveys the water to a well 50 located at the center just behind the burner face. From the well drillings 52 carrying the water to annulus 54 from which the water is discharged by drillings S6 and 58 around the bearings of the roller bit, on to exit drillings 60.

In assembly, the burner 10 is inserted into the cavity of the bit head 12 through the rear of the head. The burner 10 is rotated until the axial plane of the flame ports 23 and 24 is at right angles to the axial plane of the drill bits 28 and 29, and the burner is then locked to the bit head by locking pin 62. The bit head 12 is then screwed onto the blowpipe and the nozzle 18 seats and seals at 64 against header 14. Springs 66 urge the header 14 and nozzle 18 against packing seal 25. The header is prevented from rotating by locating pins 68.

In operation, the blowpipe is let down to contact the roller bits 28 and 29 with the mineral surface, rotation of the blowpipe is started, in either direction as shown in FIGURE 3, and the process fluids supplied to the header 14 are turned on. Oxygen through passage 15 and fuel through passage 16 are mixed at fuel injector 19, and discharged into chamber 20 where they are ignited and burned. The hot products of combustion are discharged through flame ports 23 and 24 forming high temperature high velocity flames.

The supply of fuel and oxygen is at a substantially constant rate, and the flames are continuous and at substantially constant temperature. The blowpipe is rotated at substantially constant speed in the range of from 15 to 60 revolutions per minute.

The intense heat produced which is directed against the mineral surface causes thermal softening or weakening, thereby diminishing the mechanical strength of the rock. The roller teeth 28 and 29 which are located behind the flame front, chip away the layer of rock previously weakened by the intense heat directed thereagainst.

The cooling water is employed to cool the burner 10 and the bit head 12, but is not discharged directly onto the drilling surface. That discharged through passage 46 to cool the burner face and the exterior of the cutter teeth becomes heated and has its cooling effect exhausted before it reaches the mineral surface. That discharged through bit drillings 60 becomes heated and has its cooling effect exhausted by cooling the bearings of the roller bits, before discharge against the sides of the bore hole. There the stone chips are removed from the hole by the kinetic forces of the high velocity gas and the heated water washing against the lower periphery of the hole.

Thus, applicants process heats the mineral surface and then drills the heated surface. The cooling water for the burner and drill bits does not cool the heated mineral surface. The heating flames are continuous, formed by internal combustion of liquid hydrocarbons inside the burner.

Test results are as follows:

Drilling ratei.p.m. (average rate in brackets) Mineral Quality of Not Heated to Heated to Heated to Spalling Heated 800 F. 1,400 F. 2,000 F.

Traprock Non-Spelling 5. 2 8. 95 10 9. 24

(melts). 4. 35 9. 7 14. 2(12. 5) 12. 5(10. 9) 9. 1(5. 6) 11. 5(10) 13.4 6. 45 7 5. 25

Limestone Non-Spelling 29. 3 36. 8 59 T Brittle (Oaleines). 27. 1(28. 9) 38. 4(35. 7) 47 (51) to Drill.

Opalescent Fair 12. 8 16.5 14 46.

Granite. 14. 2(15. 4) 18(18. 5) 82(64. 2)

Medium-Red Fair 9. 5 5 34.8

Leeds (Ont) 10. 5(9. 9) 13.1(13. 5) 20(21. 9) (37. 4) Granite. 10. 13 13. 4 .2 9. 5 15.1 23 2 Melrose Granite Good .7 10 19. 5 39 French Greek Good 7. 0 8.05 6.9 9. 25

Granite. 6. (6. 7) 7. 4(7. 7) 7. 15 (7. 02) 151;. 28 (10. 0)

What is claimed is:

1. Method of thermal-mechanical piercing an elongated vertical hole in a mineral body, which comprises weakening the structure of the body preparatory to mechanical drilling by applying to said body a high temperature flame to heat the mineral surface to an elevated temperature sufficiently high to cause said surface to become friable but below that at which the mineral will spall or melt, and maintaining said temperature constant by avoiding direct cooling and resultant thermally induced stresses to cause flaking, but instead, forming said chips solely by subjecting the so heated friable surface to mechanical rolling impact to remove the mineral chips and expose a new surface to said flame.

2. Method of thermal-mechanical piercing an elongated hole in a mineral body, which comprises weakening the structure of the body preparatory to mechanical rolling impact by rotating successive flames directed against the surface of said body in an annular path at from 15 to revolutions per minute to heat the mineral surface in said path to a selected temperature between 800 F. and 2000 F., said temperature being below that at which a substantial portion of the material will spall or melt but sufliciently high to cause an annular pattern of said surface to become friable and form chips upon impact, and simultaneously subjecting said friable surface in said annular path to mechanical rolling impact in rotary succession alternating every substantially 90 with said flames in said annular path.

3. Method of thermal-mechanical piercing an elongated vertical holein a mineral body, which comprises rotating successive flames directed against the surface of said body in an annular path at from 15 to 60 revolutions per minute to cause an annular pattern of said surface to become friable and preventing direct cooling of said annular pattern while simultaneously subjecting said friable surface 4. Method of thermal-mechanical piercing an elongated vertical hole in a mineral body which comprises rotating successive flames directed against the surface of said body in an annular path to cause an annular pattern of said surface to become friable without directly cooling said friable surface, and simultaneously subjecting said heated surface to mechanical rolling impact to chip said surface, said mechanical rolling impact alternating with said flames along said annular path.

5. Apparatus for thermal-mechanical piercing an elongated vertical hole in a mineral body, which comprises a blowpipe having a header for supplying fuel and oxidizing gas, a nozzle having a combustion chamber, an injector for directing said fuel and oxidizing gas to said combustion chamber, an orifice tip having flame ports from said combustion chamber for directing flames therefrom against the surface of said body, a bit head carried by said blowpipe enclosing said nozzle and orifice tip and having inwardly converging axles below said orifice tip and alternating with said flame ports, and planetary roller cutters journaled on said converging axles.

6. Apparatus for thermal mechanical piercing an elongated hole in a mineral body, which comprises a blowpipe adapted to be rotated, said blowpipe containing an internal combustion burner, said burner having flame ports for directing successive flames against the surface of said body in an annular path, said burner having passages therein for cooling fluid, a bit head carried by said blowpipe enclosing said burner and having converging axles below said flame ports with planetary roller cutters journaled on said converging axles, and means for directing jets of cooling fluid from said passages in said burner against said planetary roller cutters.

7. Apparatus for thermal mechanical piercing an elongated vertical hole in a mineral body, which comprises a blowpipe having a header for supplying fuel and oxidizing gas, a nozzle having a combustion chamber and passages for the flow of coolant, an injector for directing said fuel and oxidizing gas to said combustion chamber, means for supplying water to said passages, an orifice tip having flame port-s from said combustion chamber for directing flames therefrom against the surface of said body, a bit head carried by said blowpipe enclosing said nozzle and orifice tip and having inwardly converging axles below said orifice tip and alternating with said flame ports, planetary roller cutters journaled on said converging axles, said nozzle having drillings to direct Water from said jacket to the exterior surfaces of the cutter teeth.

References Cited by the Examiner UNITED STATES PATENTS Aitchison et al. 175-14 McKinlay 175-11 X Blood 175-14 Jackson 175-11 X Arnold et al. 175-14 Murray 175-15 Butler 175-17 Fleming 175-14 CHARLES E. OCONNELL, Primary Examiner. 

4. METHOD OF THERMAL-MECHANICAL PIERCING AN ELONGATED VERTICAL HOLE IN A MINERAL BODY WHICH COMPRISES ROTATING SUCCESSIVE FLAMES DIRECTED AGAINST THE SURFACE OF SAID BODY IN AN ANNULAR PATH TO CAUSE AN ANNULAR PATTERN OF SAID SURFACE TO BECOME FRIABLE WITHOUT DIRECTLY COOLING SAID FRIABLE SURFACE, AND SIMULTANEOUSLY SUBJECTING SAID HEATED SURFACE TO MECHANICAL ROLLING IMPACT TO CHIP SAID SURFACE, SAID MECHANICAL ROLLING IMPACT ALTERNATING WITH SAID FLAMES, ALONG SAID ANNULAR PATH. 